This invention relates to a method of supplying fuel to a plurality of cylinders of an internal combustion engine and, more particularly, to a method and a controller for supplying fuel to cylinders of a multicylinder internal combustion engine while controlling fuel injection valves provided in association with the respective cylinders.
A sequential fuel injection control system in which fuel injection valves provided in association with cylinders are sequentially controlled in synchronism with the rotation of the engine to supply fuel is known as a conventional fuel supply system for multicylinder internal combustion engines. For this sequential fuel injection control, blowing start control, i.e., control of fuel injection starting and blowing termination, i.e., control of injection termination are effected, as described, for example, on page 1004 of Jidosha Gijutsu, VOL. 39, No. 9, 1985. In this control system, however, the fuel injection rate and the injection timing are determined by the engine load determined from the intake air flow rate and the engine revolutions and so on. Ordinarily, fuel injection is effected during the exhaust stroke at each cylinder except for a transition period when the load is abruptly changed.
That is, in this conventional system, fuel injection into each cylinder of the internal combustion engine is controlled in such a manner that the required fuel injection rate is first obtained based on Qa/N which is a quotient of the intake air flow rate Qa corresponding to the engine load and the engine revolutions N, corrected with various correction coefficients, and injection is effected during the exhaust stroke at each cylinder in consideration of the injection period determined according to the fuel injection rate.
This conventional system entails a problem of an increase in the amount of total exhaust carbon compound (THC) components of exhaust gas and, hence, problems of an increase in the fuel consumption and deterioration in the operating performance at the time of starting of the engine or, more particularly, during warm-up started from a low temperature condition.